JPS5840265A - Both faces polishing device - Google Patents

Abstract

PURPOSE:To maintain the temperature of the polishing liquid constant by controlling the flow of the cooling water for cooling the polishing liquid in relative to the elapsing time of polishing. CONSTITUTION:The polishing cloths 5 are attached on the facing surfaces of the upper and lower surface plates 1, 2 and the polishing liquid 6 is provided between them. The member to be polished or the semiconductive wafer (a) is mounted on the epicyclic gear 8. The cooling water will flow from the cooling water path 12a for the upper surface plate 1 to the cooling water path 12b for the lower surface plate 2 through the cooling water circulation path 15 thus to cool the polishing liquid 6. Here the temperature of the polishing liquid 6 is detected by a temperature detector 11 then coupled to the thermometer 23 to obtain the micro factor of the temperature while the signal is provided to a pulse generator 22 such that said micro factor will reduce in inverse proportion to the polishing time and to control the flow control valve 18 by means of a stop motor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-sided bolting apparatus for bolting semiconductor wafers, for example.

II @ For driving, reserve the polisher liquid between the upper and lower surface plates, and
A polishing device that performs polishing by intervening a semiconductor wafer during O-polishing/iIl has poly-Vy/iIl on the upper and lower surface plates.
A cooling water channel is provided for cooling 11E. The temperature of the cooling water is controlled by opening and closing the inflow of cooling water into the cooling water channel, but the temperature range is 1c, and the temperature range is 1c. Difficult to keep the polishing temperature within the conventionally used method of controlling the polishing temperature by flowing cooling water into the polishing surface plate. In this method, the polishing temperature is measured using some O method, and the cooling water is turned 0N-OFF so that it reaches the set temperature*Kfi.
There are two ways to control the amount of water, and one that allows the amount of cooling water to be changed in advance in three steps (mtK) so that the amount of water can be turned off or changed at any time. However, in the method of Jin et al., it is difficult to control the polishing temperature to within 1° C. The reasons for this are the opacity of the bollising temperature, and the occurrence of hunting. In other words, in the case of ■, the amount of cooling water is supplied intermittently, so the temperature change is large. Second, the temperature changes significantly as the amount of water changes. In order to solve this difficulty, it is better to change the amount of cooling water in small increments in response to temperature changes, instead of changing the amount of cooling water large and discretely as described above. It is necessary to devise a way to make the change smoothly. On the other hand, in polishing semiconductor materials such as silicon wafers, a polishinder liquid with mechanochemical action is used, so changes in the temperature of the polishinder liquid affect processing performance, and greatly affect the stability of polishing and the dimensional and shape accuracy of polished wafers. give.

For this reason, it is important to always keep the temperature of the Boricinda solution constant and to reproduce the same polishing conditions no matter how many times the polishing is performed.

It is most accurate to directly measure the temperature of the Boricinda liquid during Borising), No. 181
As shown in 1, when the temperature of the voricinda solution when being supplied onto the polishing surface plate is constant, the temperature rise curve of the voricinda solution during polishing monotonically increases as an upwardly convex curve.

On the other hand, when polishing is performed by flowing cooling water at a constant temperature into the upper and lower surface plates at a constant flow rate, the temperature rise curve of the polycinder liquid is as shown in Figure 2. reach. Therefore, policy/
When controlling the liquid temperature to a certain set temperature, it is best to use the properties shown in Figure 2 to smoothly control the flow rate of cooling water, which will eliminate Opacity, -F1 hunting, and quickly reach the set temperature. The temperature of the liquid liquid can be controlled.

This invention was made in view of the above circumstances, and its purpose is to detect the temperature of the polishing liquid during polishing and precisely control the flow rate of the cooling water). It is an object of the present invention to provide a double-sided boring machine that can keep the temperature constant and always perform boring under constant conditions.

The present invention will be described below based on an embodiment shown in the drawings. In Fig. 3, 1 is an upper surface plate, and 2 is a lower surface plate, which are disc-shaped and each connected to a drive source (
) (not shown) so that they rotate in opposite directions. Polishing cloths 54-5 are attached to opposing surfaces of the upper surface plate 1 and the lower surface plate 2, and a polishing liquid 6 is interposed between these polishing cloths 5.5. The abrasive cloths 5, 5 are made of polyurethane-impregnated polyester nonwoven fabric, and the broaching liquid 6 is a -10.4 alkaline solution containing fine silica gel powder. Furthermore, a gear mechanism 10 is provided between the upper surface plate 1 and the lower surface plate 1, and includes planetary gears 8 and internal gears 9, which revolve around the operating sun gear 1 while rotating on their own axis. . . . A semiconductor wafer a- . . . is mounted as a material to be borated, respectively. As shown in FIG. 4, the upper surface plate IK, which faces the semiconductor wafers a, on its orbit, is provided with a through hole 1a that penetrates the polishing cloth 5, and a temperature sensor is installed in the through hole 1a. 11 is the sensing part J
Is Ja poly? /3/ da 116 is provided so as to be in contact with it. In addition, a cooling water channel Jja, 1j% is provided in a spiral shape on the upper surface plate 1 and the lower surface plate 1, and the fin #? 〇One end communicates with the flow inlet and outlet 14 provided on the rotating shafts 1 and 4.Then, the cooling water channel 1oa of the upper surface plate 1 and the cooling water channel 3j% of the lower surface plate 1 are connected in series through a cooling water circulation path 15. Furthermore, this cooling water circulation path I
A flow control valve 11 consisting of a cooling water tank 1- for keeping the temperature of the cooling water constant, a pump 11, and a needle valve for controlling the flow rate of the cooling water is provided in the middle of II. This flow rate control valve 1# is connected to a step motor 20 via a coupling 1#, and the rotation of this step motor 10 is controlled via a coupling 19 to a flow rate IIIrU control valve 181.
Furthermore, the step motor 20 is connected to a thermometer 23 via a driver 21 and a pulse generator 22. This thermometer 2J wirelessly receives an output signal from a temperature detector 11 that detects the temperature of the borising liquid 6, and provides a signal to the pulse generator 22 according to the difference between the detected temperature and the set temperature. The output signal from the pulse generator 22 is shown to be input to the step motor 20 via the output signal line driver 21.

Next, the operation of the above embodiment will be explained.

First, set the upper surface plate 1 at 45 rpm and the lower surface plate 2 at 7 Qrpr.
n.

Sun gear 1 7 orpm and internal gear 9t-
Set OrpmK and set the bore pressure to 3001.
7.,m, When the set temperature of the borising liquid 6 is set to 30°C and the borising is started, and the pump 11 is operated at the same time,
The cooling water flows through the cooling water circulation path 15 into the cooling water channel Jja of the upper surface plate 1 and the cooling water channel 11b of the lower surface plate 2 in order to cool the bolling liquid 6. At this time, the temperature is detected by the temperature sensor 11 of the point radar 1111011 during polishing, and this detection signal is input to the thermometer 28.

Now, when controlling the temperature of the polyvnoda liquid to an ideal value as shown in FIG. 5, use the polyvinyl liquid temperature differential coefficient curve shown in FIG. This #g6 diagram is a graph of the differential coefficients of the polycinder liquid temperature rise curves in Figures 1 and 2.
M8 is a case where the cooling water content is different for water-cooled models 9 and IIO, and on this graph, this curve connects the starting point of M1 and the 4 points of M4 as point 1. The point JII1w of the differential coefficient of 4 corresponds to the constant value of the temperature of the polycinder fluid that reaches the barrel when the cooling water flow rate of this one set of A-meters is supplied. Therefore, the amount of cooling water O#l is set to 1111 K.
e 9Y: Carbonization Temperature IIL If the temperature is set as shown in Figure 1, the liquid temperature IIL can be controlled to be optimal.

However, Policing during Policing 11! - The temperature is detected by temperature sensor 8., IJK.

The temperature is sampled with a thermometer 23, and the differential coefficient of the temperature is determined. Then, a signal is given from the thermometer 23 to the pulse generator 22 to generate a constant number of pulses per second so that this differential coefficient decreases in proportion to the borizing time. Therefore, the opening degree of the flow rate control valve 1t is gradually increased by the step motor 20, and the flow rate of the cooling water is increased.

Next, when the flow rate of the cooling water exceeds 81 points on the dotted line B in FIG. 6, the decrease in the differential coefficient is no longer proportional to time. Therefore, when the thermometer 23 outputs a signal to reduce the number of pulses per second, the number of pulses from the pulse generator 22 decreases by the number of pulses per second, and the opening degree of the flow rate control valve 18 gradually becomes smaller. When the sampled differential coefficient becomes zero, a signal with no pulse increase or decrease is input from the thermometer 23 to the pulse generator 22, the opening degree of the flow control valve 18 is fixed, and a constant flow of cooling water flows. . Therefore, the temperature of the polishing liquid 6 is kept constant.

Under these conditions, the dimensional accuracy of the IHD-finished wafers was measured in the butt after 50 times of double-sided polytanning. That is, the polishing time was 45 minutes, the thickness of the wafer before polishing was 680 μm, and when 4 wafers were bored at a time, 50E[I
As a result of borishing a total of 200 sheets, the thickness of the square is 6
26μm±3/Am], and the polyyyg removal rate was 1.
Very good reproducibility of 2±0.08##/ntln,
It showed stability.

In the above embodiment, the cooling water is stored in a tank and kept at a constant temperature, but if the water temperature is constant, it may be connected directly to the water supply, and if the water temperature changes, the temperature needle Based on the result of monitoring the differential coefficient, a signal may be given to the pulse generator 12 to increase or decrease the number of pulses.

As explained above, the present invention uses a flow rate control valve to vary the flow rate of the cooling water O for cooling the borishida liquid, and the flow rate control valve is controlled by an output signal from a temperature sensor that detects the temperature of the borishinda liquid. The present invention is characterized in that the flow rate of the cooling water is changed so that the differential coefficient of the poly-V powder liquid temperature is inversely proportional to the polishing time. Therefore, the temperature of the polytongue can be kept constant, and the polytongue can be produced with excellent reproducibility and stability.

[Brief explanation of the drawing]

Figures 1 and 2 are graphs showing the temperature rise curve of the Hiroborisinda liquid, Figure 3 is a cross-sectional view of a double-sided polytoning device showing an embodiment of the present invention, and Figure 4 is an enlarged view of the section ■ in Figure 3. Fig. 5 is a graph showing the temperature rise curve of the polycinda liquid, Fig. 6 is a graph showing the temperature differential coefficient curve of the polycinda liquid, and Fig. 7 is a graph showing changes in the flow rate of cooling water. . 1... Upper surface plate, 2... Lower surface plate, 12 hatake, 12b...
・Cooling water channel, 11...Temperature detector, 1#...Flow rate control valve・Applicant's representative Patent attorney Takehiko Suzue R'9': //> Two + IIIIIIfi (min) Fig. 2 - s: ° Rungu 14 Fig. 6''! Go to ゛゛〉゛〉71゛i

Claims (1)

[Claims] In a device in which a material to be polished is interposed together with a boring liquid between upper and lower surface plates that are rotatably driven, and both sides of the material to be polished are bored, cooling channels are provided in the upper and lower surface plates to cool the boring fluid. are connected in series, and a flow control valve that varies the flow rate of cooling water supplied to this cooling waterway has a mechanism driven by a pulse motor, and this flow/1 control valve is interposed between the upper and lower surface plates. A double-sided boring machine characterized in that the flow rate of cooling water is controlled by an output signal from a temperature detector that detects the temperature of a boring liquid, and the flow rate of cooling water is changed so that the differential coefficient of the temperature of the boring liquid is inversely proportional to the boring time.